Problem: Divide the following complex numbers: $\dfrac{12(\cos(\frac{5}{4}\pi) + i \sin(\frac{5}{4}\pi))}{4(\cos(\frac{11}{6}\pi) + i \sin(\frac{11}{6}\pi))}$ (The dividend is plotted in blue and the divisor in plotted in green. Your current answer will be plotted orange.)
Explanation: Dividing complex numbers in polar forms can be done by dividing the radii and subtracting the angles. The first number ( $12(\cos(\frac{5}{4}\pi) + i \sin(\frac{5}{4}\pi))$ ) has angle $\frac{5}{4}\pi$ and radius 12. The second number ( $4(\cos(\frac{11}{6}\pi) + i \sin(\frac{11}{6}\pi))$ ) has angle $\frac{11}{6}\pi$ and radius 4. The radius of the result will be $\frac{12}{4}$ , which is 3. The difference of the angles is $\frac{5}{4}\pi - \frac{11}{6}\pi = -\frac{7}{12}\pi$ The angle $-\frac{7}{12}\pi$ is negative. A complex number goes a full circle if its angle is increased by $2 \pi$ , so it goes back to itself. Because of that, angles of complex numbers are convenient to keep between $0$ and $2 \pi$ $-\frac{7}{12}\pi + 2 \pi = \frac{17}{12}\pi$ The radius of the result is $3$ and the angle of the result is $\frac{17}{12}\pi$.